Scanner not detecting Service Pack on Windows Systems

I have been carrying out the vulnerability assessment on various systems and have identified some issues which I would like to get some clarity. The VM had identified the following vulnerability on Windows XP systems.

"Microsoft SMB Remote Code Execution Vulnerability (MS05-027)"

I had carried out a scan using other prominent scanners and those scanners did not detect this vulnerability on the system. As per Microsoft relating to this vulnerability, they state that this vulnerability is applicable to Windows XP with Service Pack 1 or 2. The systems that I had scanned are already patched with SP3.

Kindly suggest why the scanner was not able to detect the SP and provide more adequate results than providing false positives.